1. a Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
2. b Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong. memwang@hku.hk
3. c Department of Orthopaedics and Traumatology, Faculty of Medicine, The University of Hong Kong, Sassoon Road, Hong Kong